Field of the Invention
The present invention relates to a liquid crystal display (LCD) apparatus, and more particularly, to an LCD apparatus for reducing a bezel width.
Discussion of the Related Art
LCD apparatuses each include a lower substrate, an upper substrate, and a liquid crystal layer formed therebetween. In the LCD apparatuses, the alignment of liquid crystal of the liquid crystal layer is adjusted with an electric field applied thereto, and thus, a light transmittance is adjusted, thereby displaying an image.
FIG. 1 is a schematic cross-sectional view of a related art LCD apparatus.
As seen in FIG. 1, the related art LCD apparatus includes an upper substrate 10, a lower substrate 20, a sealant 30, and a liquid crystal layer 40.
A light shielding pattern 12, a color filter 14, an overcoat layer 16, and an upper alignment layer 18 are formed on a bottom of the upper substrate 10.
The light shielding pattern 12 prevents light from being leaked to an area other than a pixel area. The light shielding pattern 12 is formed on the bottom of the upper substrate 10 in a matrix structure.
The color filter 14 is formed in a pixel area between adjacent light shielding patterns 12. The color filter 14 includes a red (R) color filter, a green (G) color filter, and a blue (B) color filter.
The overcoat layer 16 is formed on the light shielding pattern 12 and the color filter 14. The overcoat layer 16 is formed all over the bottom of the upper substrate 10 and enhances a surface uniformity of the bottom of the upper substrate 10.
The upper alignment layer 18 is formed on a bottom of the overcoat layer 16 and determines an initial alignment direction of the liquid crystal layer 40.
A thin film transistor (TFT) T is formed in each of a plurality of pixels on a top of the lower substrate 20, a pixel electrode 25 and a common electrode 26 are formed on the TFT T, and a lower alignment layer 28 is formed on the pixel electrode 25 and the common electrode 26. To provide a more detailed description, a gate electrode G, a gate insulation layer 22, an active layer A, a source electrode S, a drain electrode D, a passivation layer 23, a planarization layer 24, a pixel electrode 25/a common electrode 26, and the lower alignment layer 28 are sequentially formed on the lower substrate 20.
The TFT T is configured by a combination of the gate electrode G, the active layer A, the source electrode S, and the drain electrode D.
The gate insulation layer 22 is formed between the gate electrode G and the active layer A and insulates the gate electrode G from the active layer A.
The passivation layer 23 is formed on the source electrode S and the drain electrode D and protects the source electrode S and the drain electrode D.
The planarization layer 24 is formed on the passivation layer 23 and planarizes the top of the lower substrate 20.
The pixel electrode 25 is connected to the drain electrode D of the TFT T. The common electrode 26 is arranged in parallel with the pixel electrode 25 and generates an electric field along with the pixel electrode 25 to adjust an alignment direction of the liquid crystal of the liquid crystal layer 40.
The lower alignment layer 28 determines the initial alignment direction of the liquid crystal layer 40 along with the upper alignment layer 18.
The sealant 30 is formed between the upper substrate 10 and the lower substrate 20, bonds the upper substrate 10 to the lower substrate 20, and defines a space where the liquid crystal layer 40 is formed. The sealant 30 is formed at an outermost portion of the LCD apparatus.
The liquid crystal layer 40 is formed in a space between the upper substrate 10 and the lower substrate 20 defined by the sealant 30.
Recently, an effort to reduce a bezel width of an LCD apparatus is being continuously made for satisfying various requirements of consumers and improving an aesthetic appearance. A width of the sealant 30 formed at the outermost portion of the LCD apparatus should be reduced for decreasing a bezel width of the LCD apparatus. However, if a width of the sealant 30 is reduced, an adhesive force between the upper substrate 10 and the lower substrate 20 is weakened. To provide a detailed description on this, the sealant 30 is mainly adhered to the overcoat layer 16 formed on the upper substrate 10 and also is mainly adhered to the planarization layer 24 formed on the lower substrate 20. However, an adhesive force between the sealant 30 and the overcoat layer 16 is not excellent, and an adhesive force between the sealant 30 and the planarization layer 24 is not excellent. Therefore, it is required to increase a width of the sealant 30 to a certain extent or more so as to reinforce the adhesive forces which are not excellent, and for this reason, there is a limitation in reducing a bezel width of the LCD apparatus.